I was looking at this example and at line 320 the function
setFrame() does a piecewise copy of
LEAP_TRACKING_EVENT struct has a member
LEAP_HAND* pHands; which means only the pointer to the LEAP_HANDS get's copied. This might introduce unexpected behavior as the data gets overwritten in the leap motion thread.
Although I did check this with a friend as I would not expect such an obvious bug ... it makes me wonder if I'm too tired and missing something or if there is actually a bug here?